Blender 2.8 stuck on some selection mode - no idea what it is
Tap the 'W' key.

I'm suffering this problem right now. I was using 2.82 while following a tutorial based on 2.78, and heard "tap W" to get a menu to pop up for doing something.  Nope, not in 2.8 and later. These days, 'W' turns on this permanent circle select mode.